TYLER KIRK and MELISSA KIRK v. Clark Equipment Company

In the
United States Court of Appeals
For the Seventh Circuit
____________________
No. 20-2983
T YLER KIRK and MELISSA KIRK ,
Plaintiffs-Appellants,
v.
C LARK EQUIPMENT C OMPANY,
Defendant-Appellee.
____________________
Appeal from the United States District Court for the
Northern District of Illinois, Western Division.
No. 17-cv-50144 — John Robert Blakey, Judge.
____________________
A RGUED FEBRUARY 24, 2021 — D ECIDED MARCH 25, 2021
____________________
Before FLAUM, MANION, and KANNE , Circuit Judges.
FLAUM, Circuit Judge. Tyler Kirk suffered severe injuries to
his right lower leg, foot, and ankle when the skid-steer loader
he was operating for his employer tipped over. He and his
wife, Melissa Kirk (collectively, the “Kirks”), brought a strict-
liability action against the loader’s manufacturer, defendant-
appellee Clark Equipment Company, alleging a design defect
and loss of consortium. The district court granted Clark’s mo-
tions to exclude the testimony of the Kirks’ expert and for

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2 No. 20-2983
summary judgment. The Kirks appealed the district court’s
order. We now affirm.
I. Background
A. Tyler Kirk’s Accident
Tyler Kirk began working at Sterling Steel Company
(“Sterling”) in 2014. Sterling employed Kirk at its factory in
Sterling, Illinois. As part of his work duties, Kirk operated the
Bobcat Model S130 Skid-Steer Loader at issue in this suit (the
“Loader”). The Loader is a small, compact, and maneuverable
wheeled front-end loader. It is primarily used for earthmov-
ing, including digging, carrying, and dumping loose materi-
als with a bucket attachment. Sterling purchased the Loader
new in 2008 from a local dealership, rather than directly from
Clark. At the time of Kirk’s accident, it was equipped with a
sixty-two-inch bucket attachment, solid-rubber tires, rear-
axle counterweights, and a heavy rear-light guard that was
attached post sale. These components increased the Loader’s
rated operating capacity (“ROC”)—the maximum load the
Loader can carry safely and stably—to 1,420 lbs.
Kirk regularly used the Loader to clean under roll lines at
the factory. He scooped up steel scale, a byproduct of the steel
casting process, from the factory’s lower level and moved it
up a concrete ramp with approximately a thirty-degree in-
cline. Other Sterling employees used the Loader to perform
the same task, and the record indicates that no significant ac-
cidents involving the Loader occurred prior to Kirk’s acci-
dent.
Kirk’s injuries occurred on May 12, 2015, when he oper-
ated the Loader to move steel scale from the lower level to the
waste pile on the main level. After scraping the scale material

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No. 20-2983 3
from the floor into the bucket, he drove the Loader up the
ramp and approached the waste pile. Kirk asserts that the
Loader began to wobble and tip forward as he raised the
Loader’s lift arms, which held the bucket, to dump the scale
on the pile. In an effort to stabilize himself, Kirk braced his
right foot on the console near the front opening of the
Loader’s operator cab. His foot slipped out the front of the
cab, and he brought the lift-arm cross-member down on it,
crushing his foot between the cross-member and the forward
structure of the operator cab. Kirk suffered serious injuries to
his foot and ankle, requiring multiple surgeries and pro-
longed hospitalization and resulting in permanent right leg
disability, loss of his job, and medical expenses totaling
$433,000.
Kirk testified that no one else witnessed his accident;
therefore, the details of the accident come from his account.
He testified that he did not know “how full the bucket was or
how the load looked” at the time of the accident, other than
that it did not look unusually large. He stated that as he ap-
proached the waste pile, he raised the bucket to about chest
height, he could see beneath the bucket, and the load may
have extended over the top of the bucket.
B. Procedural Background
The Kirks filed a two-count complaint against Clark, alleg-
ing that Clark was strictly liable for Tyler Kirk’s injuries and
for Melissa Kirk’s loss of consortium. They alleged that the
Loader that Clark manufactured and sold to Sterling was in a
dangerous, unsafe, and defective condition for its foreseeable
use because the Loader had a propensity to tip forward when
a sixty-two-inch bucket was used to carry a heavy, dense load
such as steel scale. In bringing their claims, the Kirks invoked

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4 No. 20-2983
theories under Illinois law known as the consumer expecta-
tions test and the risk-utility test. Clark responded by filing a
third-party complaint against Sterling for contribution or in-
demnity.
The Kirks retained only one expert witness: Daniel
Pacheco. Pacheco has been employed in engineering positions
since 1964 and licensed as a professional engineer since 1970.
Pacheco, as President of Polytechnic, Inc., since 1989, provides
forensic engineering analyses of mechanical engineering is-
sues, including evaluation of the design and implementation
of material-handling equipment.
In his expert report, Pacheco rendered opinions on design
flaw and causation. Regarding design, he opined that the
Loader was “unreasonably dangerous for its intended and
foreseeable use because it had the innate propensity to not
perform as the consumer/operator would expect.” He also
stated his opinion that the Loader’s “design providing for the
use of the [sixty-two-inch low-profile] bucket … made it
highly likely, if not certain, that the bucket would be loaded
in excess of the loader’s Rated Operating Capacity of
1300/1400 lbs.” He contended that limiting the bucket to a
fifty-four-inch capacity “would have prevented exceeding the
Rated Operating Capacity … and prevented the tip forward
at the time of Mr. Kirk’s injury.”
Regarding causation, Pacheco opined that the “unreason-
ably dangerous condition” of the Loader equipped with the
sixty-two inch bucket “directly contributed to cause the leg
injury suffered by Tyler Kirk because the sudden tip forward
resulted in Mr. Kirk’s proper attempt to lower the bucket
while his leg was instinctively and inadvertently positioned

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No. 20-2983 5
in the zone where it was crushed between the descending lift
arm cross member and loader frame.”
At the close of discovery, Clark moved to exclude
Pacheco’s testimony and for summary judgment. Clark ar-
gued that Pacheco’s proffered opinions did not meet the
standards for admissibility under Federal Rule of Evidence
702. It further argued that without his testimony or the testi-
mony of another expert, the Kirks could not prove the essen-
tial elements of their claims. The district court granted both
motions, concluding that Pacheco’s opinions did not meet the
standards laid out in Rule 702 and the Supreme Court’s deci-
sion in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S.
579 (1993). The district court dismissed Clark’s third-party
complaint against Sterling as moot. 1 The Kirks then appealed.
II. Discussion
On appeal, the Kirks challenge the district court’s granting
of Clark’s motions to exclude and for summary judgment. We
begin our analysis with the motion to exclude before proceed-
ing to the summary judgment motion.
A. Exclusion of Pacheco’s Testimony
The Kirks first appeal the exclusion of Pacheco’s testi-
mony. Rule 702 and Daubert govern the admissibility of ex-
pert testimony. Haley v. Kolbe & Kolbe Millwork Co., 863 F.3d
600, 611 (7th Cir. 2017). Rule 702 provides that a witness
“qualified as an expert by knowledge, skill, experience, train-
ing, or education may testify” if:
1 Sterling is not a party on appeal.

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6 No. 20-2983
(a) the expert’s scientific, technical, or other spe-
cialized knowledge will help the trier of fact to
understand the evidence or to determine a fact
in issue;
(b) the testimony is based on sufficient facts or
data;
(c) the testimony is the product of reliable prin-
ciples and methods; and
(d) the expert has reliably applied the principles
and methods to the facts of the case.
Fed. R. Evid. 702.
In Daubert, the Supreme Court explained that Rule 702
confides to the district court a gatekeeping responsibility to
ensure that the proposed expert testimony “is not only rele-
vant, but reliable.” 509 U.S. at 589. In performing this role, the
district court must engage in a three-step analysis, evaluating:
“(1) the proffered expert’s qualifications; (2) the reliability of
the expert’s methodology; and (3) the relevance of the ex-
pert’s testimony.” Gopalratnam v. Hewlett-Packard Co., 877 F.3d
771, 779 (7th Cir. 2017) (emphasis omitted). Clark challenged,
and the district court’s order addressed, only the second
step—the reliability of Pacheco’s testimony.
When, as here, a party challenges a district court’s exclu-
sion of an expert, our review proceeds in two steps. Timm v.
Goodyear Dunlop Tires N. Am., Ltd., 932 F.3d 986, 993–94 (7th
Cir. 2019). “We review de novo whether a district judge has
followed Rule 702 and Daubert.” Haley, 863 F.3d at 611. If the
court correctly “applied the Rule 702/Daubert framework, we
review [its] decision to admit or exclude expert testimony for
abuse of discretion.” Id. Under that standard, “[s]o long as the

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No. 20-2983 7
district court adhered to Daubert’s requirements, we shall not
‘disturb the district court’s findings unless they are manifestly
erroneous.’” Naeem v. McKesson Drug Co., 444 F.3d 593, 607–
08 (7th Cir. 2006) (citation omitted). If, however, “the district
court failed to conduct a Daubert analysis, then we review de
novo whether the expert’s testimony was admissible under
Federal Rule of Evidence 702.” United States v. Adame,
827 F.3d 637, 645 (7th Cir. 2016).
1. Applicable Standard of Review
We conclude that the district court adequately performed
the Daubert analysis. “To apply the proper legal standard,
‘judges merely need to follow Daubert in making a Rule 702
determination.’” Gopalratnam, 877 F.3d at 782 (quoting Naeem,
444 F.3d at 608). A court, however, “must provide more than
just conclusory statements of admissibility or inadmissibility
to show that it adequately performed its gatekeeping func-
tion.” Gayton v. McCoy, 593 F.3d 610, 616 (7th Cir. 2010).
Here, the district court expressly recognized that “Federal
Rule of Evidence 702 and … Daubert … govern the admissi-
bility of expert testimony.” The district court “prefaced its
Daubert analysis with a … discussion of the applicable test,
which highlighted Daubert’s dual focus on relevance and reli-
ability, including the most commonly utilized reliability fac-
tors.” See Gopalratnam, 877 F.3d at 783. It also emphasized that
its analysis must focus on the principles and methodologies
underlying the expert’s conclusions. The district court pro-
ceeded to apply the Daubert factors to Pacheco’s methods and
analysis. “All told, such an inquiry stands in stark contrast to
[the] cases” cited by the Kirks in which we concluded that the
district court did not adhere to the Daubert framework. See id.
For example, in Metavante Corp. v. Emigrant Savings Bank,

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8 No. 20-2983
619 F.3d 748 (7th Cir. 2010), we applied de novo review when
the court “failed to perform a Daubert analysis” and articu-
lated only a one-sentence conclusion. Id. at 760; see also Naeem,
444 F.3d at 608 (declining to apply deferential review when
district court provided no analysis of methodology in its one-
sentence determination). Similarly, we refused to defer to
conclusory Daubert determinations in Baugh v. Cuprum S.A. de
C.V., 845 F.3d 838, 844 (7th Cir. 2017), and Fuesting v. Zimmer,
Inc., 421 F.3d 528, 534–35 (7th Cir. 2005), vacated in part on other
grounds, 448 F.3d 936 (7th Cir. 2006). The district court’s anal-
ysis here, although concise, is much more thorough than these
conclusory determinations. “Thus, we will apply an abuse of
discretion standard to our review of the court’s ultimate de-
termination to exclude [Pacheco’s] testimony.” Gopalratnam,
877 F.3d at 783.
2. The District Court’s Reliability Determination
Proceeding to the district court’s reliability determination,
we see no abuse of discretion in the exclusion of Pacheco’s
testimony. In analyzing this determination, the relevant
“question is not whether we would have admitted [Pacheco’s]
testimony in the first instance; the relevant inquiry is whether
any ‘reasonable person would agree with the decision made
by the trial court.’” Id. at 788 (quoting Smith v. Hunt, 707 F.3d
803, 808 (7th Cir. 2013)).
When evaluating the reliability of expert testimony, the
district court must make “a preliminary assessment of
whether the reasoning or methodology underlying the testi-
mony is scientifically valid.” Daubert, 509 U.S. at 592–93. A
court may consider the following non-exhaustive list of fac-
tors:

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No. 20-2983 9
(1) [W]hether the particular scientific theory
“can be (and has been) tested”; (2) whether the
theory “has been subjected to peer review and
publication”; (3) the “known or potential rate of
error”; (4) the “existence and maintenance of
standards controlling the technique’s opera-
tion”; and (5) whether the technique has
achieved “general acceptance” in the relevant
scientific or expert community.
Deputy v. Lehman Bros., Inc., 345 F.3d 494, 505 (7th Cir. 2003)
(quoting Daubert, 509 U.S. at 593–94). “No one factor is dis-
positive, however, and ‘the Supreme Court has repeatedly
emphasized [that] the Rule 702 test is a flexible one.’” Timm,
932 F.3d at 993 (alteration in original) (quoting Smith v. Ford
Motor Co., 215 F.3d 713, 719 (7th Cir. 2000)). In addition, “the
correct inquiry focuses not on ‘the ultimate correctness of the
expert’s conclusions,’ but rather on ‘the soundness and care
with which the expert arrived at her opinion.’” Id. (quoting
Schultz v. Akzo Nobel Paints, LLC, 721 F.3d 426, 431 (7th Cir.
2013)).
As an initial matter, the Kirks assert that the district court
conducted a flawed Daubert analysis by neglecting to address
Pacheco’s qualifications. Although an expert’s qualifications
represent the first prong of the required three-prong Daubert
inquiry, see Gopalratnam, 877 F.3d at 779, neither Clark nor the
district court questioned Pacheco’s qualifications. The Kirks
nonetheless dedicate a substantial portion of their briefing on
appeal to arguing that Pacheco is qualified to offer expert
opinions. To the extent that they assert that Pacheco’s qualifi-
cations alone render his testimony admissible, that argument
misreads our precedent.

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10 No. 20-2983
A court’s determination that an expert possesses the req-
uisite qualifications does not, without more, provide a suffi-
cient basis for admissibility. See Ford Motor Co., 215 F.3d at 718
(“A court’s reliability analysis does not end with its conclu-
sion that an expert is qualified to testify about a given mat-
ter.”). We have underscored that “[e]ven ‘[a] supremely qual-
ified expert cannot waltz into the courtroom and render opin-
ions unless those opinions are based upon some recognized
scientific method.’” Id. (some alterations in original) (quoting
Clark v. Takata Corp., 192 F.3d 750, 759 n.5 (7th Cir. 1999)). The
district court cases the Kirks cite in their briefing do not indi-
cate otherwise; in those cases, the district courts determined
whether to admit or exclude expert testimony by considering
several factors, only one of which was the expert’s qualifica-
tions. See Schuring v. Cottrell, Inc., 244 F. Supp. 3d 721, 728–32
(N.D. Ill. 2017); Hasan v. Cottrell, Inc., No. 10 C 5534, 2014 WL
4124254, at *3–7 (N.D. Ill. Aug. 21, 2014); Traharne v.
Wayne/Scott Fetzer Co., 156 F. Supp. 2d 697, 703–17 (N.D. Ill.),
aff’d and adopted, 156 F. Supp. 2d 717 (N.D. Ill. 2001); Lichter v.
Case Corp., No. 99 C 4260, 2001 WL 290615, at *2–3 (N.D. Ill.
Mar. 20, 2001); Moncrieffe v. Clark Equip. Co., No. 06-22644-
CIV, 2008 WL 11333222, at *6–10 (S.D. Fla. July 23, 2008). That
process of analysis accords with Daubert’s instructions. The
district court here thus appropriately proceeded to the relia-
bility determination, and we now also address each of
Pacheco’s proffered opinions in turn.
a. Pacheco’s defective condition opinion
Pacheco first opined that the Loader was defective only if
equipped with a sixty-two-inch bucket because the size of the
bucket allows it to carry a load so heavy that it causes the
Loader to tip over. The district court excluded this opinion as

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No. 20-2983 11
unreliable. On appeal, the Kirks argue that the district court
erred by overlooking Pacheco’s citation to and reliance on
various industry standards and publications, Clark’s own
testing data, and additional testimony.
We disagree; the district court’s finding was within its dis-
cretion. Pacheco’s conclusion that the Loader had a design de-
fect when equipped with a sixty-two-inch bucket hinged on a
load weight in the bucket exceeding the ROC. Based on his
own calculations and those of a Sterling engineer regarding
the density of steel scale and the volume of the sixty-two-inch
bucket filled both to the “struck” line (level with the sides of
the bucket) and to a “heaped” capacity (above the sides),
Pacheco opined that it was “highly likely” that a heaped load
of steel scale in a sixty-two-inch bucket would exceed the
Loader’s ROC, while a struck load would not. He then con-
cluded that a heaped load, in conjunction with the Loader’s
short wheelbase, would cause a propensity for the Loader to
tip forward.
The district court, however, considered and found unreli-
able the evidence Pacheco cited to support his opinion that
the Loader had a design defect. The district court made clear
that it reviewed and analyzed Pacheco’s report and deposi-
tion testimony, both of which set out and explained the bases
for and methodologies underlying his conclusions—as the
Kirks admit. It emphasized the absence of data from similar
accidents, generally accepted industry standards, and peer re-
view to support Pacheco’s conclusion. Pacheco had never
used a skid-steer loader (let alone the Loader in question)
with a bucket attachment to pick up and move materials nor
had he ever operated a skid-steer loader at full operating ca-
pacity or tipped a skid-steer loader forward. Thus, Pacheco

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12 No. 20-2983
did not test his design defect theory on either the Loader or
any similar loaders or equipment. The court accordingly
found that the only identifiable source for Pacheco’s opinion
that a defect existed was his own speculation. While terse, the
district court’s analysis tracked the Daubert factors and found
that they weighed against admissibility.
The Kirks also argue that the district court overlooked ad-
ditional evidence, but that evidence still would not provide
sufficient support to overcome the shortcomings in Pacheco’s
opinion. First, the Kirks point to the deposition testimony of
Marvin Smith, a co-worker of Tyler Kirk’s, and Robert
Merema, an employee at one of Clark’s distributors. The ad-
missibility (and probative value) of this testimony is doubtful
because neither Smith nor Merema witnessed the accident or
provided any indication that they had experienced substan-
tially similar accidents. See Nachtsheim v. Beech Aircraft Corp.,
847 F.2d 1261, 1268 (7th Cir. 1988) (explaining the “founda-
tional requirement” in product liability cases that “the propo-
nent of similar accidents evidence must establish substantial
similarity before the evidence will be admitted” is of particu-
lar importance when the evidence is proffered to show “the
existence of a dangerous condition or causation”). Smith tes-
tified that he experienced bouncing while operating the
Loader with full loads; he did not testify that he tipped over
while operating the Loader, or that he had maneuvered a sim-
ilar load as Kirk. Merema testified that he was aware of a gen-
eral trend of all skid-steer loaders to tip forward, but he spe-
cifically disclaimed any personal knowledge of or experience
with other tipping or bouncing incidents.
Second, the Kirks point to the evidence of Sterling’s sub-
sequent remedial measure of replacing the sixty-two-inch

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No. 20-2983 13
bucket with a fifty-four-inch bucket. This evidence is inadmis-
sible under Federal Rule of Evidence 407, which prohibits the
admission of evidence of subsequent remedial measures to
show culpability. See Traylor v. Husqvarna Motor, 988 F.2d 729,
733 (7th Cir. 1993).
Finally, the Kirks point to industry literature that Pacheco
relied on in his report and testimony. That literature is irrele-
vant because it simply states the general fact that “forward
tipping of skid steer loaders … has been one of the most fre-
quent causes of injury and death from use of such equipment”
and advises on safe operating procedures to reduce the risk
of tipping. Pacheco did not state that this literature specifi-
cally addresses the Loader at issue here or whether equipping
it with a sixty-two-inch bucket renders the Loader defective.
The evidence highlighted by the Kirks thus does not
clearly support the reliability of Pacheco’s opinion that the
Loader was unreasonably dangerous when equipped with a
sixty-two-inch bucket. We therefore conclude that the district
court’s decision to exclude Pacheco’s opinion regarding the
purported defect was not manifestly erroneous.
b. Pacheco’s causation opinion
Pacheco also opined that the unreasonably dangerous
condition of the Loader equipped with the sixty-two-inch
bucket directly contributed to Tyler Kirk’s injuries. The dis-
trict court similarly excluded this opinion as unreliable. It
found that an “analytical gap exists between the fact that
overloaded buckets on skid-steer loaders can cause a loader to
tip and the conclusion that this particular Loader’s 62-inch
bucket caused the overloading and subsequent tipping in this
instance.” The court found that Pacheco did not know the

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14 No. 20-2983
weight of the Loader’s bucket at the time of the accident, let
alone whether it exceeded the ROC, and that he performed no
testing on the Loader or a similar loader to confirm his causa-
tion theory. It also emphasized the absence of evidence of
peer review or general acceptance of the theory. Finally, the
district court found that Pacheco’s analysis did not account
for “obvious potential alternative causes.” The Kirks contend
that the record refutes each of these findings.
We again conclude that the district court acted within its
discretion. Pacheco’s opinion that an overloaded bucket
caused the Loader to tip, injuring Tyler Kirk, rests on his spec-
ulation that the weight of the load exceeded the ROC. Yet, by
his own admission, Pacheco did not know the weight of the
load in the bucket at the time of the accident and could not
say whether it exceeded the ROC.
The Kirks maintain that the inability to determine the ex-
act weight of the load does not render Pacheco’s opinion in-
admissible because his opinion still represents a reasonable
judgment based on the knowable facts regarding the amount
and weight of scale in the bucket. This contention is unavail-
ing. First, it appears that Pacheco based his assumption that
the weight of the load exceeded the ROC on a mischaracteri-
zation of Tyler Kirk’s testimony. Pacheco stated that Kirk tes-
tified that “the bucket was full and that the machine began to
tip.” In fact, Kirk testified that the load “didn’t look unusually
large,” but it was “possible” that the load extended over the
top of the bucket. See Bielskis v. Louisville Ladder, Inc., 663 F.3d
887, 896 (7th Cir. 2011) (explaining that district court may as-
sess whether it “‘was appropriate for [an expert] to rely on the
test that he administered and upon the sources of information
which he employed’” (citation omitted)). For his own part,

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No. 20-2983 15
Pacheco gave contradictory testimony about whether the load
remaining in the bucket post-accident appeared “heaping.”
Second, the Kirks’ argument that Pacheco appropriately
calculated the load’s weight using the bucket’s dimensions
fares no better because of the scale material’s irregularity. We
have acknowledged that an expert may sometimes draw a
conclusion based on only their “extensive and specialized ex-
perience.” See id. (quoting Kumho Tire Co., Ltd. v. Carmichael,
526 U.S. 137, 156 (1999)). An expert, however, must “substan-
tiate his opinion,” rather than assume it to be true. See Takata
Corp., 192 F.3d at 757 (quoting Huey v. United Parcel Serv., Inc.,
165 F.3d 1084, 1087 (7th Cir. 1999)). Here, Tyler Kirk testified
that no two loads of steel scale fit the same in the bucket be-
cause “[steel scale is] an irregular material” with respect to its
shape, and Merema, the Clark distributor employee, testified
that “[y]ou’d almost have to … go over a scale with” the
Loader to determine the weight in the bucket. That testimony
undercuts the reliability of Pacheco’s calculations based on
generic evidence. Indeed, Pacheco even conceded that, while
not expected, it would have been possible for Kirk to tip the
Loader forward with a load in the bucket weighing at or be-
low the ROC.
More generally, Pacheco’s testimony provided ample rea-
son to question the “soundness and care” with which he ar-
rived at his opinion on causation. See Schultz, 721 F.3d at 431.
He did not view, inspect, or operate the Loader in person. He
never visited the Sterling factory or inspected the accident site
beyond photographs. He did not interview Tyler Kirk, the
only eyewitness to the accident and only person with
knowledge of how it occurred. He testified that he did not
know Kirk’s speed at the time of the accident, other than in

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16 No. 20-2983
imprecise terms. Finally, Pacheco testified that none of his
opinions have been peer-reviewed.
The district court also did not err in concluding that
Pacheco did not rule out any serious alternative causes. Alt-
hough Pacheco opined that Kirk operated the Loader in a
manner consistent with the training and operating manuals
provided by Clark—and that his opinion was corroborated by
Clark’s expert—Pacheco testified that he could not “point to
any specific” reason why Kirk’s operation of the Loader did
not contribute to causing the accident. Pacheco also conceded
that in addition to not knowing Kirk’s speed at the time of the
accident, he could not conclusively state whether Kirk had
cleared the ramp before the accident and did not verify the
grade of the ramp. Moreover, Pacheco did not address the fact
that no other similar accidents involving the Loader occurred
over the seven years preceding Kirk’s accident. Pacheco’s fail-
ure to account for and investigate potential alternative causes
lends additional support to the district court’s reliability de-
termination. See, e.g., Gopalratnam, 877 F.3d at 787 (affirming
exclusion of expert in part because he “failed to account for
other possible explanations in arriving at his conclusion”);
Brown v. Burlington N. Santa Fe Ry. Co., 765 F.3d 765, 774 (7th
Cir. 2014) (affirming exclusion of expert for failing to investi-
gate and rule out any serious alternative causes).
The Kirks advance several arguments in support of the ad-
missibility of Pacheco’s causation opinion. First, they argue
that the question of causation constitutes an ultimate question
of fact that a jury, not the court, should resolve. Therefore,
they contend that the fact that Pacheco based his opinion on
evidence supporting his opinion suffices to clear the Daubert
threshold. “The purpose of Daubert,” however, “was to

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No. 20-2983 17
require courts to serve as gatekeepers so that unreliable ex-
pert testimony does not carry too much weight with the jury.”
United States v. Ozuna, 561 F.3d 728, 737 (7th Cir. 2009). At the
Daubert phase, then, “[t]he ultimate question is whether the
expert’s approach is scientifically valid.” Kopplin v. Wis. Cent.
Ltd., 914 F.3d 1099, 1103–04 (7th Cir. 2019). “The focus is on
the expert’s methodology, not his ultimate conclusions.” Id. at
1104. Here, the district court concluded that Pacheco’s prof-
fered testimony regarding his methodology, which bears on
an ultimate question of fact, lacked sufficient indicia of relia-
bility. Accordingly, it was appropriate for the court to exclude
that testimony. See Daubert, 509 U.S. at 595 (explaining that
“[e]xpert evidence can be both powerful and quite misleading
because of the difficulty in evaluating it” (citation omitted)).
Second, the Kirks suggest that Pacheco did not need to test
his opinions because Sterling replaced the sixty-two-inch
bucket with a smaller bucket after the accident. They first as-
sert that inspection or testing of the Loader “would provide
no relevant information.” This blanket assertion, however, is
belied by precedent and the facts of the case. While absence
of testing represents only one factor in the Daubert analysis,
when combined with the lack of other supporting data or peer
review, it may weigh against a finding of reliability. Further-
more, relevant to a case based on an alleged design defect in
the Loader, inspection and testing of the Loader may very
well have provided Pacheco with additional, valuable infor-
mation in forming his causation opinion.
Third, the Kirks argue that testing should not be required
when it would be fruitless or impossible. We do not require
experts to accomplish the impossible or to use cost-prohibi-
tive methods. See id. at 593 (“[A] key question to be answered

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18 No. 20-2983
in determining whether a theory or technique is scientific
knowledge that will assist the trier of fact will be whether it
can be (and has been) tested.” (emphasis added)); see also
McCloud ex rel. Hall v. Goodyear Dunlop Tires N. Am., Ltd.,
479 F. Supp. 2d 882, 892 (C.D. Ill. 2007) (“To meet the testing
factor required by Daubert an expert does not need to perform
the best conceivable test. Instead, the question is whether
valid scientific testing was performed.”). Here, however, the
Kirks did not provide sufficient support for their conclusory
argument that they could not recreate the conditions of Tyler
Kirk’s accident. The district court thus did not abuse its dis-
cretion in declining to credit that argument.
In sum, based on the facts in the record, we conclude that
the district court did not abuse its discretion in excluding
Pacheco’s causation opinion.
B. Summary Judgment
The Kirks also appeal the district court’s grant of summary
judgment for Clark. We review de novo a district court’s or-
der granting summary judgment. See Skiba v. Ill. Cent. R.R. Co.,
884 F.3d 708, 717 (7th Cir. 2018). “Summary judgment is ap-
propriate when there is no genuine dispute as to a material
fact and the movant is entitled to judgment as a matter of
law.” Estate of Jones v. Child.’s Hosp. & Health Sys. Inc. Pension
Plan, 892 F.3d 919, 923 (7th Cir. 2018).
The district court here concluded that Pacheco’s exclusion
doomed the Kirks’ claims under Illinois strict-liability law.
That law requires a plaintiff to prove “(1) a condition of the
product as a result of manufacturing or design, (2) that made
the product unreasonably dangerous, (3) and that existed at
the time the product left the defendant’s control, and (4) an

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No. 20-2983 19
injury to the plaintiff, (5) that was proximately caused by the
condition.” Clark v. River Metals Recycling, LLC, 929 F.3d 434,
439 (7th Cir. 2019) (quoting Mikolajczyk v. Ford Motor Co.,
901 N.E.2d 329, 345 (Ill.), opinion modified on denial of reh’g (Ill.
2008)). The district court determined that without Pacheco’s
testimony, the Kirks failed to raise a triable issue on the first
and fifth elements—an unreasonably dangerous design and
causation. The Kirks assert on appeal that they raised suffi-
cient questions of material fact to submit this case to a jury
even without expert testimony.
Our review begins and ends with design defect. In Illinois,
a plaintiff may establish a design defect through two different
approaches: “the consumer-expectations test and the risk-
utility test.” Id. “But if the evidence before the court implicates
the risk-utility test, it is the one that the court should use, ‘be-
cause the latter [i.e. the consumer-expectations test] is incor-
porated into the former and is but one factor among many for
the jury to consider.’” Id. (alteration in original) (quoting
Mikolajczyk, 901 N.E.2d at 352).
In addition, Illinois courts recognize that “[p]roducts lia-
bility actions … often involve specialized knowledge or ex-
pertise outside the layman’s knowledge” and so may require
expert testimony. See Baltus v. Weaver Div. of Kidde & Co.,
557 N.E.2d 580, 588–89 (Ill. App. Ct. 1990); see also Show v. Ford
Motor Co., 659 F.3d 584, 585 (7th Cir. 2011) (“Several interme-
diate appellate decisions in Illinois say that expert testimony
is vital in design-defect suits when aspects of a product’s de-
sign or operation are outside the scope of lay knowledge.”).
Accordingly, while “there might be some products that are so
simple that no expert is needed to tell people how to use
them,” cases involving specialized or complex products

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20 No. 20-2983
“can[not] be resolved exclusively on the basis of common ex-
perience” and require “expert testimony for this critical ele-
ment of [a plaintiff’s] case (i.e. what design(s) would have
been acceptable).” River Metals, 929 F.3d at 440.
In this case, the district court concluded that “the Loader
is not a simple product that lay jurors commonly see or use,
but a specialized piece of industrial equipment that falls out-
side of a juror’s common understanding and experiences.”
We agree with that finding, which is supported by relevant
precedent. See, e.g., id. (affirming summary judgment when
plaintiff lacked expert testimony on whether a car crusher had
an unreasonably defective design that caused plaintiff’s slip-
and-fall injury); Show, 659 F.3d at 588 (affirming summary
judgment when plaintiff lacked expert testimony regarding
whether car had a design defect that rendered it unstable and
caused it to roll over); Henry v. Panasonic Factory Automation Co.,
917 N.E.2d 1086, 1092 (Ill. App. Ct. 2009) (affirming summary
judgment when plaintiff lacked expert testimony on whether an
industrial machine was unreasonably dangerous); Fulton v.
Theradyne Corp., No. 06 C 1321, 2007 WL 772953, at *4 (N.D. Ill.
Mar. 12, 2007) (granting summary judgment on design defect
claim when the plaintiff failed to present admissible expert evi-
dence regarding the design of a medical device); cf. River Metals,
929 F.3d at 440 (noting that a product such as a chair might be
“so simple” such that expert testimony is unnecessary to explain
to a jury why its design renders it unreasonably dangerous).
Because we agree that this product lies outside the layper-
son’s expertise, the Kirks needed expert testimony to prove
that the Loader’s design rendered it unreasonably dangerous.
The district court, however, did not abuse its discretion in ex-
cluding Pacheco, the Kirks’ only expert. The Kirks thus lack
evidence to prove their product-liability allegations based on

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No. 20-2983 21
a strict-liability theory. Accordingly, we conclude that the dis-
trict court appropriately granted summary judgment. See
River Metals, 929 F.3d at 440 (“[T]he case before us is not one
that can be resolved exclusively on the basis of common ex-
perience. [The plaintiff] needed expert testimony for this crit-
ical element of his case (i.e. what design(s) would have been
acceptable), and with [the proposed expert’s] analysis ex-
cluded, he had none. Summary judgment … followed natu-
rally.”).
The Kirks argue that they can prove design defect under
the consumer-expectations test without expert testimony be-
cause an ordinary consumer could determine what caused the
Loader to tip. This argument overlooks the fact that we have
previously rejected the contention that “jurors, as consumers,
can find in their own experience all of the evidence required
for liability under the [Illinois] consumer-expectation ap-
proach.” Show, 659 F.3d at 585. We concluded that if “it takes
expert evidence to establish a complex product’s unreasona-
ble dangerousness through a risk-utility approach, it also
takes expert evidence to establish a complex product’s unrea-
sonable dangerousness through a consumer-expectations ap-
proach.” Id. at 587. “Because consumer expectations are just
one factor in the inquiry whether a product is unreasonably
dangerous, a jury unassisted by expert testimony would have
to rely on speculation.” Id. at 588. Accordingly, the Kirks’ lack
of admissible expert testimony to prove that a design defect
in the Loader rendered it unreasonably dangerous is fatal to
their suit under either the consumer-expectations or risk-util-
ity theory.

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22 No. 20-2983
III. Conclusion
For the reasons explained above, we AFFIRM the district
court’s order granting Clark’s motion to exclude Pacheco’s
testimony and entering summary judgment for Clark.

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